The invention disclosed herein relates generally to postage scales adapted to weigh an article and determine the appropriate postage to be applied thereto. Specifically the present invention is directed to a postal scale and a cable having the ability to communicate with incompatible devices.
Various postal systems for automatically determining proper postage and interfacing with mailing system peripherals are well known in the art. One such system is disclosed in U.S. Pat. No. 4,395,756 issued to Edward P. Daniels, on Jul. 26, 1983, which describes a microprocessor based system with: a keyboard and display; a scale subsystem processor forming part of a weighing cell, for providing weight information in digital form to the system processor; and, a plurality of peripheral postal devices interfaced to the postal system processor. Another similar system is disclosed in U.S. Pat. No. 4,603,400 issued to Edward P. Daniels on Jul. 29, 1986, disclosing a microprocessor based system with: a keyboard and display; a scale weighing device operatively connected to the system processor; and, postage printing subsystem and peripheral subsystem processors connected to the system processor through a serial communications interface.
The above systems are fully integrated systems and designed to interface with compatible machines. The fully integrated systems are not capable of functioning separately nor are they interchangeable with other peripheral systems.
A need to interface postal scale mailing systems with a variety of mailing system peripherals has developed in an effort to satisfy customer requests for combining incompatible systems to provide personalized mailing solutions. These systems often operate under different protocols and thus, are incompatible U.S. Pat. No. 4,642,791 issued to Mallozzi et al., on Feb. 10, 1987 presents one solution to this problem. This patent discloses an interface that provides communication between a weighing cell providing weight information in the form of code digits representative of arbitrary weight units and optically coupled interface adapter ports which have separate input and output lines.
Another such system is disclosed in U.S. Pat. No. 4,301,507 issued to John H. Soderberg on Nov. 17, 1981, disclosing a serial communications port and a plurality of external devices in which the communications procedure disclosed relates to serial transmission of data and bit by bit return of such data to the transmitter verification. A daisy chain is operatively connected between a plurality of external devices and an associated control is described. However, a communications buffer comprising a daisy chain undesirably prolongs the period of time for transmission of data and increases the possibility of a transmission error.
Yet another such solution is described in U.S. Pat. No. 4,410,961 issued to Dlugos et al., on Oct. 18, 1983 which discloses an interface adapted to interconnect the system processor with a plurality of mailing system peripheral devices. The interface includes a peripheral micro-computer which receives data and command signals from the processor of a scale which communicates through an Echoplex protocol. A multiplexer interconnects the peripheral transmit line of the microcomputer with a selected peripheral device, while an additional multiplexer interconnects the peripheral receive line of the microcomputer with the selected peripheral device. However, only communication between an Echoplex scale and either Echoplex or RS232 peripheral devices is disclosed. A significant disadvantage with this system is that this system requires the user to predetermine and preselect what communication subroutines are necessary to be implemented in order to achieve successful communication. However, with the introduction of a scale which communicates through PB232 protocol a need arose to convert the PB232 protocol to Echoplex protocol.
Multi-cable interfaces as described in the prior art are difficult to install, aesthetically unappealing, and costly. Moreover, interfaces that are attached between cables connecting the incompatible device are expensive and after confusing to the customer during assembly. Increased customer interest in customizing systems has prompted greater interest to provide an inexpensive easy to assemble method and device for enabling incompatible systems to communicate. A further need has developed to provide an interface between a postage value determining system processor such as a PB232 scale and a plurality of peripheral devices associated with a mailing system having either PB232 or ECOPLEX protocols which allows the system processor to communicate irrespective of the processor protocol.
Other objects and advantages of the present invention will be apparent from the detailed description considered in conjunction with the preferred embodiment of the invention illustrated in the drawings, as follows.
The present invention discloses a smart cable assembly interconnected between a postage scale system configured to detect a plurality of peripheral devices and to communicate with the peripheral devices regardless of the individual device protocol. The present invention includes a postage value determining system processor connected via a smart cable to a plurality of peripheral devices having a variety of mailing system protocols. The peripheral protocol may be either PB232 protocol or Echoplex protocol. Once the scale determines whether the peripheral protocol is Echoplex or PB232, the scale establishes communication between the PB232 scale and the variety of peripheral devices, by converting the PB232 scale protocol to the protocol of the peripheral device, such as for example, either Echoplex or RS232 protocol.
The scale detects which signal protocol is in present operation. Based upon detecting what signal is received from the peripherals, the scale then switches to the postage system signal, which corresponds to the-signal of the peripheral, thus enabling communication. In typical operation, the postage scale is an RS232 protocol while the mailing system peripherals are either RS232 protocol or Echoplex protocol. RS232 and Echoplex protocols are well known in the art, a detailed description of the individual protocols is not necessary for an understanding of this invention. In general, PB232 protocol is a variation of the RS232 Protocol. Not all the signals are used however, voltage levels are the same.
The scale includes a circuit board that has both an RS232 to Echoplex converter, and an Echoplex to RS232 converter. The scale maintains a physical connection through a to the peripheral device through physical ports.
In one method of operation, the scale, detects the peripheral protocol, switches the protocol of the scale to correspond to the peripheral device and then outputs the proper message to the peripheral device.
The cable contains trip circuitry to allow scales communicating via PB232, the ability to not only set Echoplex or PB232 protocol, but, also to trip a mailing machine for printing postage. When a set dollar value amount is transmitted to an electronic postage meter, a request for the value set is then transmitted to the meter. The microcomputer awaits receipt of a signal indicating the amount which has been set by the meter; this value is then transmitted to the system processor for comparison with the set value originally transmitted. Upon a trip command, the microcomputer transmits a trip signal to a mailing machine for tripping the meter and awaits receipt of a meter trip complete signal from the postage meter. In the present invention, the mailing machine trip may originate from the cable or from the peripheral device depending upon whether a PB232 protocol or an Echoplex protocol is transmitted.
A plurality of communications subroutines are stored in the microcomputer program memory. Thus, versatility in the selection of peripherals which may be employed in conjunction with a stand-alone postage scale is desirable and by present invention available. A system output line is provided for communications with a peripheral device employing either the RS232 or Echoplex communications.